1. Cross-reference to Related Applications
The present application is related to the co-pending application of Thomas S. Wilmeth, Steven L. Wilmeth and Frances E. Foster entitled METHOD FOR MAKING SUCKER ROD OIL PUMP, U.S. patent application Ser. No. 07/383,019, filed Jul. 19, 1989.
2. Field of the Invention
This invention relates generally to sucker rod oil well pumps of the type having hardened metal layers on the plunger and barrel components thereof and, more specifically, to an improved chrome plating process for depositing a chromium deposit of desired thickness on the barrel of such a sucker rod pump.
3. Description of the Prior Art
Sucker rod well pumps have been in wide use for many years. A barrel is mounted to the tubing. The barrel has a smooth cylindrical bore. A plunger is positioned inside the tubing and connected to the sucker rod. The sucker rod is reciprocated up and down to move the plunger in the barrel. A stationary check valve is located at the bottom of the barrel. A traveling valve is located at the bottom of the plunger. The valves cooperate on the downstroke and upstroke to pump fluid from the well to the surface.
The mating surfaces between the plunger and barrel provide a very close fit. In wells which produce abrasive particles, such as quartz or sand, these particles can quickly damage the mating surfaces. The wear due to the abrasive particles will cause leakage past the plunger. This necessitates the pump being pulled for replacement at fairly frequent intervals.
Various techniques have been used in the past to increase wear resistance. In one technique, a chrome case is plated on either of the barrel or the plunger. Circumferential grooves have also been formed in the plunger.
In the previously referenced application entitled METHOD FOR MAKING SUCKER ROD OIL WELL PUMP, U.S. patent application Ser. No. 07/383,019, filed Jul. 19, 1989, a sucker rod pump is shown having hardened layers to increase wear resistance. The barrel has a chromium case plated on its bore and a plunger which has a boronized case. The plunger also has circumferential grooves spaced-apart from each other. The chromium case is plated in a conventional manner, except that it is about twice the thickness of the chromium cases placed in conventional barrels of sucker rod pumps. Preferably, the layer is from about 0.006 to 0.008 thickness on each side.
Despite the previous advances, a need exists for a process for improving the wear resistance of the components of a sucker rod well pump in order to extend the useful life thereof.